Ferrite magnetic material, ferrite magnet, and ferrite sintered magnet

ABSTRACT

A ferrite magnet and a ferrite sintered magnet including a ferrite magnetic material are provided. A main phase of the ferrite magnetic material includes a ferrite phase having a hexagonal crystal structure, and metal element composition expressed by Ca1-w-x-yR wSr xBayFezMm wherein 0.25&lt;w&lt;0.5, 0.01&lt;x&lt;0.35, 0.0001&lt;y&lt;0.013, y&lt;x, 8.7&lt;z&lt;9.9, 1.0&lt;w/m&lt;2.1, 0.017&lt;m/z&lt;0.055 and Si component is at least included as a sub-component, and wherein; when content y1 mass % of the Si component in the ferrite magnetic material, with respect to SiO2, is shown on Y-axis and a total content x1 of z and m is shown on X-axis, a relation between x1 and y1 is within a range surrounded by 4 points placed on X-Y coordinate having the X and Y axes.

This application is a continuation of application Ser. No. 13/520,270filed Jul. 2, 2012, which is a National Stage Application ofPCT/JP20111056091 filed Mar. 15, 2011, and claims the benefit ofJapanese Patent Application Nos. 2010-061302 filed Mar. 17, 2010 and2011-002288 filed Jan. 7, 2011. The entire disclosures of the priorapplications are hereby incorporated by reference herein in theirentirety.

TECHNICAL FIELD

The present invention relates to a ferrite magnetic material and to aferrite magnet and a ferrite sintered magnet respectively comprising theferrite magnetic material.

BACKGROUND ART

As for a permanent magnet material comprising oxide, hexagonal M-type(Magnetopulmbite-type) Sr ferrite or Ba ferrite are known. Ferritemagnetic material comprising such ferrites is provided as a permanentmagnet in a form of ferrite sintered body or bond magnet. Recently, witha size-reduction and higher performance of electronic device, a demandfor permanent magnet comprising ferrite magnetic material to have highermagnetic property, even with further reduction in size, is increasing.

As for an indicator of magnetic property shown by permanent magnet,residual flux density (Br) and coercive force (HcJ) are generally used;and it is evaluated that the higher they are the higher their magneticproperty is. Conventionally, in order to increase Br and HcJ ofpermanent magnets, studies have been conducted by varying itscomposition such as by adding predetermined elements in ferrite magneticmaterial.

For instance, Patent Document 1 discloses an oxide magnetic materialwhich can provide a ferrite sintered magnet having high Br and HcJ, byadding at least La, Ba and Co to M-type Ca ferrite.

Further, Patent Document 2 discloses an oxide magnetic material whichcan provide a ferrite sintered magnet having high Br and HcJ, by addingat least La, Sr and Co to M-type Ca ferrite. Furthermore, PatentDocument 3 discloses a sintered magnet having high Br and HcJ, by addingat least Sr, La and Co to M-type Sr ferrite.

PRIOR ARTS Patent Documents

-   [Patent Document 1] Japanese Patent No. 4078566-   [Patent Document 2] WO Publication No. 2007/077811-   [Patent Document 3] Japanese Patent No. 3163279

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

As mentioned above, in order to obtain both good Br and HcJ, althoughthere has been instigated many attempts at variously changingcombinations of elements added to main composition, it is still notobvious that which combination of the added element provide a highmagnetic property.

Further, as for a permanent magnet, in addition to having high Br andHcJ, it is preferable that ratio of a value (Hk) in magnetic field whenmagnetization to HcJ is 90% to that of Br, i.e. squareness ratio(Hk/HcJ), is also high. When Hk/HcJ is high, demagnetization due toouter magnetic field or temperature change is small; thus a stablemagnetic property can be obtained.

Therefore, it is preferable that permanent magnet using ferrite magneticmaterial can obtain high Br and HcJ, along with superior Hk/HcJ.However, it was not easy to obtain ferrite magnetic material which canprovide a permanent magnet having such 3 magnetic properties because,for instance, when one magnetic property improved the other magneticproperty deteriorated.

Further, in order to heighten Br, it is effective to align directions ofan easy axis of magnetization (c-axis direction of hexagonal crystalstructures, when M-type ferrite is used.) of crystal grains constitutingferrite phase, namely, to improve orientation of an easy axis ofmagnetization and to make anisotropy form. However, when saidorientation improves, with M-type ferrite, crystal grains tend to growin a direction of a hard axis of magnetization, which is perpendicularto the an easy axis of magnetization; and thus, aspect ratio shown by aratio of an average crystal grain size in axis of hard magnetizationdirection and that in an easy axis of magnetization, tends to becomehigh. When said aspect ratio becomes high, it tends to be effected bydemagnetization in crystal grains. Further, an increase of an averagecrystal grain size in a hard axis of magnetization direction indicates adecrease in number of crystal grains, which become a single-domaincritical size (Approximately 1 μm in the case of M-type ferrite.). Withthese effects, HcJ tends to decrease and it becomes difficult tomaintain both high Br and HcJ.

Therefore, the invention was made considering the above situations; andits object is to provide a ferrite magnetic material, which can providepermanent magnet wherein a high Br and HcJ are maintained, and inaddition, a high Hk/HcJ is provided, and to provide a magnet comprisingsaid ferrite magnetic material.

Means to Solve the Problem

In order to achieve such object, ferrite magnetic material of thepresent invention is a ferrite magnetic material, in which its mainphase comprises ferrite phase having a hexagonal crystal structure andit is shown by a metal element composition expressed by the followingformula (1),

Ca_(1-w-x-y)R_(w)Sr_(x)Ba_(y)Fe_(z)M_(m)  (1)

wherein R in formula (1) is at least one element selected from a groupconsisting of rare-earth element (Y is included) and Bi, which at leastincludes La, M in formula (1) is at least one element selected from agroup consisting of Co, Mn, Mg, Ni, Cu and Zn, which at least includesCo,

w, x, y, z and m in formula (1) respectively satisfies the followingformulas (2), (3), (4), (5), (6), (7) and (8)

0.25<w<0.5  (2)

0.01<x<0.35  (3)

0.0001<y<0.013  (4)

y<x  (5)

8.7<z<9.9  (6)

1.0<w/m<2.1  (7)

0.017<m/z<0.055  (8), and

Si component is at least included as a sub-component, and wherein;

when content y1 of the Si component in the ferrite magnetic material,with respect to SiO₂, is shown on Y-axis and total content x1 of _(z)and _(m) is shown on X-axis, a relation between x1 and y1 is within arange surrounded by 4 points a(8.9, 1.2), b(8.3, 0.95), c(10.0, 0.35)and d(10.6, 0.6), placed on X-Y coordinate having the X and Y axes.

Ferrite magnetic material of the present invention is shown by the aboveformula (1), each element satisfies formulas (2) to (8), and Sicomponent is further included as subcomponent; characterized in thatwhen y1 mass % of the Si component in the ferrite magnetic material,with respect to SiO₂, is shown on Y-axis and total content x1 of _(z)and _(m) is shown on X-axis, a relation between x1 and y1 is within arange surrounded by 4 points a(8.9, 1.2), b(8.3, 0.95), c(10.0, 0.35)and d(10.6, 0.6), placed on X-Y coordinate having the X and Y axes; andthus, a ferrite magnet or a ferrite sintered magnet having not only highBr and HcJ but also high Hk/HcJ can be obtained.

Degree of crystal orientation Or(f)=Σ(001)/Σ(hkl) of the ferrite magnetor the ferrite sintered magnet, obtained by X-ray diffractionmeasurement, is preferably 0.9 or more.

Preferably, within a cut surface of crystal grains constituting theferrite magnet or the ferrite sintered magnet, which is cut by a planeparallel to c-axis direction of hexagonal crystal structures, maximumand minimum values of grain size which go through a gravity center ofeach grains in the crystal cross-section are respectively obtained; andthen, when an average of said maximum and minimum values of the sizes incrystal grains of a predetermined number or more are respectivelydetermined as L(μm) and S(μm), said L and S satisfy the followingformulas (9) and (10).

L≦1.4  (9)

L/S≦2.4  (10)

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a figure showing a relation between x1 and y1 for each sampleof the present examples on the X-Y coordinate having X and Y axes, whena total amount x1 of z and in is shown on X-axis and content y1 mass %of Si component with respect to SiO₂ in the ferrite magnetic material isshown on Y-axis.

FIG. 2 is a sectional view of crystal grains describing a measuringmethod respectively of crystal grain sizes and aspect ratio of crystalgrains constituting ferrite sintered magnet according to one embodimentof the invention.

FIG. 3(A) is a sectional SEM picture of a ferrite sintered magnetaccording to an example of the invention. FIG. 3(B) is a sectional SEMpicture of a ferrite sintered magnet according to a relative example ofthe invention.

FIG. 4 is a sectional view of a main part of magnetic field injectionmachine, used for a manufacturing sintered magnet according to anembodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be explained hereinafter.

(Ferrite Sintered Magnet)

Ferrite magnetic material constituting ferrite sintered magnet accordingto an embodiment of the present invention has a main phase comprisingferrite phase having hexagonal crystal structure. As for the ferritephase, Magnetopulmbite-type (M-type) ferrite, referred to as “M-typeferrite” hereinafter, is preferable. Note that a main phase comprisingMagnetopulmbite-type (M-type) ferrite is particularly called as“M-phase”. Although ferrite sintered magnet generally comprises “a mainphase (crystal grains)” and “grain boundary part”, “a main phasecomprising ferrite phase” described here indicates “main phase” is aferrite phase. Ratio of the main phase in sintered body is preferably 95volume % or more.

Ferrite magnetic material constituting ferrite sintered magnet is asintered body form as is described hereinbefore, and has a structurecomprising crystal grains (main phase) and grain boundary. An averagecrystal grain size of crystal grains in said sintered body is preferably1.4 μm or less, more preferably 0.5 to 1.4 μm. With such average crystalgrain sizes, high HcJ can be easily obtained. Note that “average crystalgrain size” is an arithmetic mean value of grain sizes in a hard axis ofmagnetization (a-axis) direction of crystal grains in M-type ferritesintered body. The crystal grain size of ferrite magnetic materialsintered body can be measured by scanning electron microscope.

Ferrite magnetic material according to an embodiment of the inventionhas a metal element composition shown by the following formula (1)

Ca_(1-w-x-y)R_(w)Sr_(x)Ba_(y)Fe_(z)M_(m)  (1)

Note that R in formula (1) is at least one element selected from a groupconsisting of rare-earth element, including Y, and Bi, which at leastincludes La, and M is at least one element selected from a groupconsisting of Co, Mn, Mg, Ni, Cu and Zn, which at least includes Co.

In formula (1), w, x, y, z and in respectively shows an atomic ratio ofR, Sr, Ba, Fe and M, and respectively satisfies the following formulas(2), (3), (4), (5), (6), (7) and (8).

0.25<w<0.5  (2)

0.01<x<0.35  (3)

0.0001<y<0.013  (4)

y<x  (5)

8.7<z<9.9  (6)

1.0<w/m<2.1  (7)

0.017<m/z<0.055  (8)

Further, ferrite magnetic material, as for a sub-component besides themetal element composition mentioned hereinbefore, at least includes Sicomponent. As is shown in FIG. 1, when a content y1 mass % of the Sicomponent in the ferrite magnetic material, with respect to SiO₂, isshown on Y-axis and total amount x1 of z and m is shown on X-axis, arelation between x1 and y1 is within a range surrounded by 4 pointsa(8.9, 1.2), b(8.3, 0.95), c(10.0, 0.35) and d(10.6, 0.6), placed on X-Ycoordinate having the X and Y axes.

Note that compositional ratio of oxygen is affected by compositionalratio of each metal element and valence of each element (ion), andincreases and decreases to maintain electroneutrality in crystals.Further, during the firing process described hereinafter, oxygen defectmay occur when firing atmosphere is made to a reduced atmosphere.

Hereinafter, said ferrite magnetic material composition will bedescribed in detail.

Ca atomic ratio (1-w-x-y) in metal element composition constituting theferrite magnetic material is preferably more than 0.25 and less than0.59. When Ca atomic ratio is too small, ferrite magnetic material maynot become M-type ferrite.

Further, in addition to an increase of ratio of non-magnetic phase, suchas α-F₂O₃, R may exceed and different phase of non-magnetic, such asorthoferrite, may generate and magnetic properties (particularly Br andHcJ) tend to decrease. While when Ca atomic ratio is too large, inaddition to not being M-type ferrite, non-magnetic phase, such asCaFeO_(3-x), may increase and thus, magnetic properties may decrease.

Ferrite sintered magnet according to the present embodiment may furtherinclude the other subcomponent, in addition to an subcomponent of SiO₂,as is described hereinafter. For example, Ca component may be includedas a subcomponent. Note that, ferrite sintered magnet according to thepresent embodiment includes Ca as a component constituting ferrite phaseas a main phase as mentioned hereinbefore. Therefore, when Ca isincluded as subcomponent, for example, Ca amount analyzed from asintered body is a total amount included in the main phase and thesubcomponent. Namely, when Ca component is used as a subcomponent, Caatomic ratio (1-w-x-y) in general formula (1) will be a value in whichthe subcomponents are included. Range of the atomic ratio (1-w-x-y) isdetermined based on a composition analyzed after sintering, and thus, itcan be applied both to when Ca component is included and when Cacomponent is not included.

An element shown by R at least includes La. In addition to said La, atleast one kind selected from a group consisting of rare-earth element,including Y, and Bi is preferable, and at least one kind selected from agroup consisting of rare-earth element is more preferable. However, asfor R, it is particularly preferable to include only La in order toimprove anisotropy magnetic field.

Atomic ratio (w) of R in metal element composition constituting theferrite magnetic material is more than 0.25 and less than 0.5. Withinthis range, Br, HcJ and Hk/HcJ can be well obtained. When atomic ratioof R is too small, solubility amount of M in ferrite magnetic materialbecomes insufficient, which leads to a decrease of Br and HcJ. Whilewhen too large, different phase of non-magnetic, such as orthoferrite,occur, and Hk/HcJ decreases, which becomes difficult to obtain practicalmagnet. With these points of view, atomic ratio of R is preferably 0.3or more to less than 0.5, and more preferably 0.3 to 0.45.

Atomic ratio (x) of Sr is over 0.01 and less than 0.35; and within thisrange, Br, HcJ and Hk/HcJ can be well obtained. When atomic ratio of Sris too small, ratio of Ca and/or La tends to become large and Hk/HcJdecreases. While when atomic ratio of Sr is too large, Br and HcJ becomeinsufficient. With these points of view, it is preferable that atomicratio of Sr is 0.05 to 0.25, and it is more preferable to be 0.1 to 0.2.

Atomic ratio (y) of Ba is over 0.0001 and less than 0.013; and withinthis range, Br, HcJ and Hk/HcJ can be well satisfied. When atomic ratioof Ba is too small, a sufficient improvement effect of Hk/HcJ cannot beobtained. While when too large, Br and HcJ become inconvenientlyinsufficient. With these points of view, it is preferable that atomicratio of Ba is 0.0004 to 0.01.

Further, atomic ratio (x) of Sr and atomic ratio (y) of Ba satisfy arelation y<x. By making atomic ratio of Sr larger than that of Ba, itbecomes easy to obtain sufficiently high Hk/HcJ, in addition to obtaingood Br.

Atomic ratio (z) of Fe is over 8.7 and less than 9.9; and within thisrange, Br, HcJ and Hk/HcJ can be well satisfied. When said atomic ratioof Fe is too small or too large, Br and HcJ inconveniently decrease. Itis preferable that atomic ratio of “Fe” is 8.8 to 9.6.

An element shown by M at least includes Co, and in addition, it ispreferable to include at least one kind selected from a group consistingof Mn, Mg, Ni, Cu and Zn, and it is more preferable to include at leastone kind selected from a group consisting of Mn, Ni and Zn. However, asfor M, it is particularly preferable to include only Co in order toimprove anisotropy magnetic field.

Metal element composition constituting ferrite magnetic material,considering atomic ratio (m) of M, satisfies a condition in which m/z ismore than 0.017 and less than 0.055. Further, w/m satisfies a conditionof being more than 1.0 and less than 2.1. By satisfying theseconditions, Br, HcJ and Hk/HcJ can be well obtained. When atomic ratioof M is too small, good Br or HcJ cannot be obtained; particularly whenCo ratio is too small, good HcJ cannot be obtained. While when ratio ofM is too large, Br and HcJ rather tend to decrease.

With these points of view, m/z is preferably 0.02 to 0.035. Further, w/mis preferably 1.2 to 1.9, more preferably 1.4 to 1.8.

Ferrite magnetic material of the invention includes subcomponentsdescribed hereinafter, in addition to the metal element compositiondescribed hereinbefore. The subcomponents may be included in both mainphase and grain boundary of ferrite magnetic material. All components inthe ferrite magnetic material, except for the subcomponent, are maincompositions. In order to obtain sufficient magnetic property, contentratio of main phase in ferrite magnetic material is preferably 90 mass %or more, more preferably 95 to 100 mass %.

Ferrite magnetic material of the present embodiment includes at least Si(silicon) component as a subcomponent. Here, the Si component includesboth Si atom itself and a mixture including Si, such as SiO₂. As forSi-included mixture, SiO₂, Na₂SiO₃, SiO₂.nH₂O, etc. can be exemplified,although it is not particularly limited if it has a compositionincluding Si. When Si component is included in ferrite magneticmaterial, sintering ability becomes good and crystal grain size ofsintered body will be suitably adjusted; and thus, magnetic propertiesof the ferrite sintered magnet will be well controlled. And as a result,high Hk/HcJ can be obtained while maintaining good Br and HcJ.

Ferrite magnetic material of the present embodiment, as is shown in FIG.1, when y1 mass % of the Si component in the ferrite magnetic material,with respect to SiO₂, is shown on Y-axis and total amount x1 of z and mis shown on X-axis, a relation between x1 and y1 is within a rangesurrounded by 4 points a(8.9, 1.2), b(8.3, 0.95), c(10.0, 0.35) andd(10.6, 0.6), placed on X-Y coordinate having X and Y axes.

When a relation of x1 and y1, namely a relation of Si component ratioand a total amount of z and m, is within said range, good Br, HcJ andHk/HcJ can be obtained. When content amount of Si component is toolarge, a large amount of non-magnetic Si component will be included inferrite sintered magnet; and there is a tendency to decrease magneticproperties, particularly Br. While when Si component is too small, goodeffects mentioned hereinbefore cannot be obtained; and that HcJ tends todecrease.

Total content amount of Si component in ferrite magnetic material of theinvention, with respect to SiO₂, is preferable 0.35 to 1.2 mass %, morepreferably 0.4 to 1.1 mass %. When content amount of Si component iswithin the above range, a high HcJ can be obtained.

Although ferrite magnetic material comprises the metal elementcomposition and the subcomponent at least including Si component, theferrite magnetic material composition can be measured by a fluorescenceX-ray quantitative analysis. Further, existence of main phase can beconfirmed by X-ray diffraction or electron diffraction.

Ferrite magnetic material of the present embodiment may include acomponent other than Si component as a subcomponent. As for the othersubcomponent, Al and/or Cr can be included, for instance. With thesecomponents, HcJ of ferrite sintered magnet tends to increase. In termsof obtaining a good enhancing effect of HcJ, content amount of Al and/orCr, with respect to Al₂O₃ or Cr₂O₃, is preferably 0.1 mass % or more ofthe total ferrite magnetic material. Note that these components maydecrease Br of ferrite sintered magnet; therefore, 3 mass % or less ispreferable in terms of obtaining good Br.

As for a subcomponent, boron B can be included as B₂O₃, for instance. Byincluding B, pre-calcining temperature when obtaining ferrite magneticmaterial and firing temperature when obtaining sintering body of ferritemagnetic material can be decreased, which lead to increased productivityof ferrite sintered magnet. However, when B is too large, saturatedmagnetization of ferrite sintered magnet may decrease. Thus, contentamount of B of the total ferrite magnetic material, with respect toB₂O₃, is preferably 0.5 mass % or less.

Furthermore, ferrite magnetic material of the present embodiment mayinclude Ga, Mg, Cu, Mn, Ni, Zn, In, Li, Ti, Zr, Ge, Sn, V, Nb, Ta, Sb,As, W, Mo, etc. in an oxide form as subcomponent. Content amountsthereof are preferably, with respect to oxides of stoichiometriccomposition for each atom, 5 mass % or less of gallium oxide, 5 mass %or less of magnesium oxide, 5 mass % or less of copper oxide, 5 mass %or less of manganese oxide, 5 mass % or less of nickel oxide, 5 mass %or less of zinc oxide, 3 mass % or less of indium oxide, 1 mass % orless of lithium oxide, 3 mass % or less of titanium oxide, 3 mass % orless of zirconium oxide, 3 mass % or less of germanium oxide, 3 mass %or less of tin oxide, 3 mass % or less of vanadium oxide, 3 mass % orless of niobium oxide, 3 mass % or less of tantalum oxide, 3 mass % orless of antimony oxide, 3 mass % or less of arsenic oxide, 3 mass % orless of tungsten oxide and 3 mass % or less of molybdenum oxide.However, when a combination of multiple kinds thereof is included, inorder to avoid a decrease of magnetic properties, it is desirable that atotal amount thereof is 5 mass % or less.

Ferrite magnetic material of the present embodiment is preferable not toinclude alkali metal element, such as Na, K, Rb, etc., as subcomponent.Alkali metal element tends to decrease saturated magnetization ofmagnet 1. However, alkali metal element may be included in raw materialsof ferrite magnetic material; and thus, it can be included in theferrite magnetic material at inevitably included amount. Content amountof the alkali metal element which does not largely affect magneticproperties is 3 mass % or less.

(Degree of Crystal Orientation of Ferrite Sintered Magnet)

Ferrite sintered magnet according to the present embodiment, degree ofcrystal orientation Or(f)=Σ(001)/Σ(hkl) measured by X-ray diffraction(XRD) is preferably 0.9 or more, and more preferably 0.92 or more.

Measuring method of degree of the crystal orientation Or(f) will bedescribed hereinafter. First, for instance, one surface of circularplated or cylindrical molded ferrite sintered magnet is polishedsmoothly, XRD measurement is performed on the smoothly polished surface,and by obtaining diffraction patterns, diffraction peak derived fromferrite sintered magnet will be identified. And then, degree ofcrystallographic orientation (degree of X-ray) of ferrite sinteredmagnet will be obtained from plane indices and peak strength of thediffraction peaks.

Note that, in the present invention, degree of crystal orientation offerrite sintered magnet is determined as Or(f)=ΣI(00L)/ΣI(hkL). (00L) inthe formula is an indication collectively referred to as c-plane (aplane perpendicular to c-axis) in crystal structure, such as (004),(006), etc. ΣI(00L) indicates a total of all the peak strength toward(00L) surface. Further, (hkL) indicates all the detected diffractionpeaks, and ΣI(hkL) is a total of peak strength thereof.

Further, c-plane indicated by (00L) is a plane perpendicular to an easyaxis of magnetization direction in ferrite sintered magnet of thepresent embodiment. The higher the total peak strength of (00L) planeis, namely, the higher the Or(f)=ΣI(00L)/ΣI(hkL) is, axes of easymagnetization will be aligned crystallographically, and thus, Br will beimproved.

(Crystal Grains of Ferrite Sintered Magnet)

Ferrite sintered magnet according to the present embodiment, as is shownin FIG. 2, is constituted from crystal grains having ellipticalcross-section. In a cut surface cut by a plane parallel to c-axisdirection of hexagonal crystal structures, of the crystal grainsconstituting ferrite sintered magnet according to the presentembodiment, maximum and minimum values of grain sizes which go through agravity center of each grains in the crystal cross-section arerespectively obtained; and then, when an average of a predeterminednumber or more of crystal grains is determined as L(μm), S(μm), said Land S preferably satisfy the following formulas (9) and (10).

L≦1.4  (9)

L/S≦2.4  (10)

As for a range of L, L≦1.37 is preferable, and 0.6≦L≦1.37 is morepreferable. As for a range of L/S, L/S≦2.35 is preferable, and1.7≦L/S≦2.35 is more preferable.

Said L/S is a parameter often called as aspect ratio. When degree oforientation in M-type ferrite become high, crystal grains tend to growin a direction of a hard axis of magnetization (a-axis of hexagonalcrystal structure, S direction in FIG. 2), which is perpendicular to aneasy axis of magnetization (c-axis of hexagonal crystal structure, Ldirection in FIG. 2) direction. Therefore, aspect ratio, which shows aratio of an average crystal grain size in the direction of a hard axisof magnetization direction and that of an easy axis of magnetizationdirection, is easy to become higher. And then, when said aspect ratiobecome high, it becomes easy to be affected by demagnetization incrystal grains. Further, an increase of average crystal grain size inthe direction of a hard axis of magnetization direction indicatesdecrease of crystal grain numbers, which become single-domain criticalsize (approximately fpm in the case of M-type ferrite). With theseinfluences, HcJ tends to decrease, and it becomes difficult to obtainboth high Br and high HcJ.

However, according to ferrite magnetic material of the presentembodiment, both high Br and high HcJ can be maintained by satisfyingconditions shown by the above formulas (9) and (10).

Hereinafter, an average maximum grain size L and an average minimumgrain size S will be described in detail by referring FIGS. 2 and 3.M-type ferrite, as is mentioned above, has an easy axis of magnetizationin c-axis direction of hexagonal crystal structures. Therefore, in orderto measure average maximum grain size L and average minimum grain sizeS, a cross-section parallel to c-axis direction of hexagonal crystalstructures, of ferrite sintered magnet is cut out. Next, mirrorpolishing and etching treatment by hydrofluoric acid were performed tothe cross-section. Crystal grain boundary part is removed by the etchingtreatment, which makes observation of crystal grains easy. Next, thecross-section is observed by scanning electron microscope (SEM) andgrain sectional image parallel to c-axis direction of hexagonal crystalstructures, will be observed. An example of the obtained cross-sectionalimage will be shown in FIG. 3( a).

Subsequently, an image analysis process is performed to grain sectionalimage, and for each crystal grains, maximum and minimum values ofcrystal grains, which go through a gravity center of the graincross-section are respectively measured. In the present embodiment, asis shown in FIG. 2, maximum grain size 1(μm), which is a maximum valueof a grain size going through gravity center J of grain cross-section ofone crystal grain 20, and minimum grain size s(μm), which is a minimumvalue of a grain size going through gravity center J of graincross-section of one crystal grain 20, are respectively obtained.

Then, arithmetic mean value respectively of the maximum grain size andthe minimum grain size with a predetermined number of crystal grains arecalculated; and then, they were respectively determined as averagemaximum grain size L and average minimum grain size S. Note that apredetermined number of crystal grains in order to obtain the mean valueis preferably 500 or more.

Further, as for a magnet comprising ferrite magnetic material of thepresent embodiment, it is not limited to the aforementioned ferritesintered magnet, and such as bond magnet, in which ferrite magneticmaterial powder is combined with binder, can be exemplified.

In case of the bond magnet, the aforementioned conditions of ferritemagnetic material can be satisfied with ferrite magnetic materialpowder. An average particle size of ferrite magnetic material powder isnot particularly limited; however, 2 μm or less is preferable, 1.5 μm orless is more preferable, and 0.1 to 1 μm is further preferable. Whenthis average particle size is too large, a ratio of multi-domainparticles in the powder become higher, and HcJ is likely to decrease.While when the average particle size is too small, magnetic propertydecreases by thermal disturbance, and orientation and formability maydecrease when molding in a magnetic field.

As for a binder, nitrile rubber (e.g. NBR rubber), chlorinatedpolyethylene, polyamide resin (e.g. nylon 6®, nylon 12®), etc. can beexemplified.

(Manufacturing Method of Ferrite Sintered Magnet)

In the embodiment below, an example of manufacturing method of ferritesintered magnet comprising ferrite magnetic material is shown. In thepresent embodiment, ferrite sintered magnet can be manufactured throughprocesses of mixing process, calcining process, milling process, moldingprocess and firing process. Further, drying and kneading processes ofmilled slurry may be included between the milling process and themolding process. Degreasing process may be included between the moldingprocess and the firing process. Each process will be described below.

<Mixing Process>

In the mixing process, raw materials of ferrite magnetic material aremixed to obtain raw material mixture. As for a raw material of ferritemagnetic material, compound (raw material compound) comprising one ortwo element constituting the raw material can be exemplified. As for araw material compound, such as powder form is preferable. As for the rawcompound, an oxide of each element or a compound (carbonate, hydroxide,nitrate, etc.) which become an oxide after firing can be exemplified.For instance, SrCO₃, La(OH)3, Fe₂O₃, BaCO₃, CaCO₃, Co₃O₄, etc. can beexemplified. An average particle size of raw material compound powder isapproximately 0.1 to 2.0 μm is preferable, in view of obtaining auniform mixture, for instance.

As for a raw material of Si component in ferrite magnetic material, SiO₂can be exemplified, however, it is not particularly limited, if they arecompounds including Si. Further, as for a raw material powder, rawmaterial compound (an element alone, an oxide, etc.) of the othersubcomponent can be mixed when necessary.

As for the mixture, for instance, each raw material were weighed toobtain a composition of the desired ferrite magnetic material, mixed,and then, mixed and milled for approximately 0.1 to 20 hours by usingsuch as wet-attritor and ball mill.

Note that, all the raw materials are not necessary to be mixed in themixing process, and a part of the materials can be added after thebelow-mentioned calcining process. For instance, raw material of Si(e.g. SiO₂) as subcomponent and raw material of Ca (e.g. CaCO₃) asconstituting element of metal element composition can be added duringmilling (particularly fine-milling) process after the below-mentionedccalcining process. Timing of the addition can be adjusted in order toeasily obtain the desired composition and magnetic property.

<Calcining Process>

In calcining process, mixture obtained by the mixing process arecalcined. Calcination is preferably performed in oxidizing atmosphere,such as air. The calcination temperature is preferably within the rangeof 1100 to 1400° C., more preferably 1100 to 1300° C., further morepreferably 1150 to 1300° C. The stabilizing time at the calcinationtemperature can be 1 sec. to 10 hours, preferably 1 sec. to 5 hours.Calcined body obtained by the calcination comprises 70% or more of theaforementioned main phase (M-phase). Initial particle size of thecalcined body is preferably 10 μm or less, more preferably 5 μm or less,further more preferably 2 μm or less.

<Milling Process>

In the milling process, the granular or massive calcined body aftercalcining process is milled to reproduce a powdery form. With thisprocess, it becomes easy to form in the molding process describedhereinafter. With this milling process, raw material, which was notmixed in the mixing process, can be added (after adding raw materials)as is mentioned hereinbefore. The milling process, for example, can beperformed in a two-step process, in which calcined body is milled(coarse-milling) to make a coarse powder, and then, further finelymilled (fine-milling).

The coarse milling is performed by using such as vibrational mill untilan average particle size becomes 0.5 to 5.0 μm. The fine milling isperformed by further pulverizing the coarse milled material obtainedfrom the coarse milling by wet-attritor, ball mill, jet mill, etc. Inthe fine milling, fine milling is performed until an average particlesize of the obtained fine milled material become preferablyapproximately 0.08 to 2.0 μm, more preferably approximately 0.1 to 1.0μm, furthermore preferably approximately 0.1 to 0.5 μm. Specific surfacearea (obtained such as by BET method) of fine milled material ispreferably approximately 4 to 12 m²/g. Preferable time for thepulverizing varies according to the used pulverizing method. Forinstance, approximately 30 min. to 20 hours are preferable for awet-attritor and 10 to 50 hours are preferable for a wet-milling by aball mill.

When adding a part of raw material in the milling process, for example,addition can be performed during the fine milling. In the presentembodiment, SiO₂ as Si component or CaCO₃ as Ca component may be addedduring the fine milling, however, they may also be added during themixing process or the coarse milling process.

In the fine milling process, non-aqueous solvent, such as toluene andxylene in addition to water, can be used as a dispersant in case of awet process. There tends to obtain a high orientation during the wetformation described hereinafter, when using the non-aqueous solvent. Onthe other hand, the aqueous solvent is preferably used in view ofproductivity.

Further, in the fine milling process, in order to increase degree oforientation of the sintered body after firing, polyalcohol shown by ageneral formula such as C_(n)(OH)_(n)H_(n+2) may be added. Here, as forthe polyalcohol, n in the general formula is preferably 4 to 100, morepreferably 4 to 30, furthermore preferably 4 to 20, and particularlypreferably 4 to 12. As for the polyalcohol, sorbitol can be exemplified.Further, polyalcohol of two or more kinds can be used. Furthermore, inaddition to the polyalcohol, combined usage of the other well-knowndispersants is possible.

When adding the polyalcohol, the additional amount is, with respect toadding object (e.g. coarse milled material), preferably 0.05 to 5.0 mass%, more preferably 0.1 to 3.0 mass % and furthermore preferably 0.2 to2.0 mass %. Polyalcohol added during the fine milling process is removedby heat decomposition during firing process mentioned hereinafter.

Note that, as for a molding method of the milled material (preferablethe fine milled material), when using the following CIM (CeramicInjection Molding), namely PIM (Powder Injection Molding), the additionof polyalcohol such as sorbitol during drying the milled slurry maybecome a cause for a remarkable occurrence of powder aggregation or fora powder dispersant in binder resin, which is not preferable. In thiscase, no dispersant may be added or powder may be surface treated by adispersant comprising hydrophilic group and hydrophobic (lipophilic)group in a same molecule, such as silane coupling agent. Additionalamount of the dispersants may be 0.3 to 3.0 mass % with respect toadding object (e.g. coarse milled material). Although these dispersantsare preferably added to the fine milled slurry and mixed, it is notparticularly limited the example and said dispersants can be added afterdrying or during kneading process with a binder resin.

<Molding•Firing Process>

In the molding•firing process, after molding the milled material(preferably fine milled material) obtained after the milling process andobtaining molded body, the molded body is fired to obtain sintered body.Molding can be performed with dry molding, wet molding or CIM. In thecase of dry molding method, for instance, magnetic field is appliedduring pressure molding the dried magnetic powder, obtaining the moldedbody, and then the molded body is fired. In the case of the wet moldingmethod, for instance, slurry including magnetic powder is pressuremolded in a magnetic field, a liquid component is removed, obtaining amolded body, and then the molded body is fired.

Note that, in general, with the dry molding method, dried magneticpowder is pressed in a mold and that a required time for molding processis short, which is preferable. However, an improvement of degree oforientation of magnetic powder in a magnetic field during the molding isdifficult; thus, magnetic properties of the resultant sintered magnet isinferior to that of the sintered magnet obtained from the wet moldingmethod. Further, with the wet molding method, although magnetic powdertends to orientate by magnetic field when molding and magneticproperties of the sintered magnet are good, there remains a problem thatit takes time for molding since liquid components must be withdrawn whenapplying pressure.

Further, CIM is a method wherein a dried magnetic powder is heat kneadedtogether with a binder resin the pellet is formed, a preliminary moldedbody is obtained by injection molding the pellet in a mold wheremagnetic field is applied, and firing after removing binder treatment isapplied to the preliminary molded body.

Molding method of ferrite magnetic material according to theaforementioned embodiment is not particularly limited; however, CIM andwet molding are preferable, and CIM is particularly preferable. CIM andwet molding will be described below in detail.

(CIM•Firing)

When obtaining ferrite sintered magnet by CIM method, after a wetmilling, the milled slurry including magnetic powder is dried. Dryingtemperature is preferably 80 to 150° C., more preferably 100 to 120° C.Drying time is preferably 1 to 40 hours, more preferably 5 to 25 hours.An average particle size of initial magnetic powder after drying ispreferably within a range of 0.08 to 2 μm, more preferably within arange of 0.1 to 1 μm.

The dried magnetic powder is kneaded together with binder resin, waxes,smoothing agent, plasticizing agent, sublimation compound, etc.(referred to as organic component hereinafter), and then formed to apellet by such as pelletizer. The organic component is included in themolded body preferably by 35 to 60 volume %, more preferably 40 to 55volume %. Kneading can be performed such as by kneader, etc. As for thepelletizer, for instance, a Twin Screw Extruder can be used. Thekneading and pelletizing can be performed by heating, depending onmelting temperature of used organic component.

As for a binder resin, a high-molecular compound such as thermoplasticresin can be used. As for a thermoplastic resin, polyethylene,polypropylene, ethylene-vinyl acetate copolymer, atacticpolypropylene,acrylic polymer, polystyrene, polyacetal, etc. are used.

As for the waxes, other than natural waxes such as carnauba wax, montanwax and bees wax, synthetic waxes such as paraffin wax, urethane wax andpolyethylene glycol are used.

As for a smoothing agent, such as fatty acid ester may be used, and asfor the plasticizing agent, such as phthalate ester may be used.

An additional amount of the binder resin is preferably 3 to 20 mass %,an additional amount of waxes is preferably 3 to 20 mass % and anadditional amount of smoothing agent is preferably 0.1 to 5 mass %, withrespect to 100 mass % of magnetic powder. An additional amount ofplasticizing agent is preferably 0.1 to 5 mass % with respect to 100mass % of binder resin.

In the present embodiment, for instance, pellet 10 is injection moldedin the mold 8 field injection molding device 2 in a magnetic field as isshown in FIG. 4. Before the injection in the mold 8, the mold 8 isclosed, cavity 12 is molded inside the mold 8, and magnetic field isapplied in the mold 8. Note that pellet 10 is entered from a portion 4to extruder 6 and heat melted to such as 160 to 230° C. inside extruder6 and injected in cavity 12 of mold 8 by a screw. Temperature of themold 8 is 20 to 80° C. Applied magnetic field to mold 8 is approximately398 to 15921 KA/m (5 to 20 kOe).

Next, the preliminary molded body obtained by CIM is heat treated at 100to 600° C. in air or in nitrogen; and binder removing treatment isperformed to obtain a molded body. When binder treatment is insufficientor heating rate is rapid when removing binder, breaks or cracks mayoccur in a molded body or a sintered body due to a rapid volatilizationor an occurrence of decomposition gas of the aforementioned organiccomponents. Therefore, depending on the organic components used forremoving binder, heating rate within a temperature range, in whichvolatilization or decomposition is performed, can be suitably adjustedto a slow heating rate such as 0.01 to 1° C./min., and then binder maybe removed. On the other hand, when binder is excessively removed, shaperetention of the molded body become insufficient and chip may be molded;therefore, it is required to control heat treatment temperature ortemperature profile. Further, when several kinds of organic componentsare used, removing binder treatment can be performed for a severaltimes.

Next, in the sintering process, molded body after the binder treatmentis sintered in air preferably at 1100 to 1250° C., and more preferably1160 to 1230° C. for approximately 0.2 to 3 hours, and then ferritesintered magnet of the present invention is obtained. When temperatureis too low or temperature holding time is too short, desired magneticproperties cannot be obtained due to the following reasons, such assufficient density of the sintered body cannot be obtained or reactionof the added element is insufficient. Further, when firing temperatureis too high or temperature holding time is too long, desired magneticproperties cannot be obtained as well, due to reasons such as abnormalgrowth of crystal grains or an occurrence of different phase other thanM-type ferrite. Note that the firing process can be performedconsecutively with binder removing process or the firing can beperformed once the temperature is cooled to a room temperature after thebinder removing treatment.

(Wet Molding Firing)

When a ferrite sintered magnet is obtained by a wet molding method, forinstance, it is preferable that slurry is obtained by the aforementionedfine milling process by wet process; subsequently slurry for a wetmolding is obtained by concentrating said slurry to a predeterminedconcentration; and then molding is performed using the slurry thereof.The slurry concentration may be performed by such as a centrifugation ora filter press. Slurry for wet molding, fine milled material ispreferably around 30 to 80 mass % with respect to the total amount. Inthe slurry, water is preferable for a dispersant dispersing fine milledmaterial. In this case, surface acting agents, such as gluconic acid,gluconate and sorbitol, may be added to the slurry. Non-aqueous solventmay be used for the dispersant. Organic solvents such as toluene, xylen,etc. may be used as the non-aqueous solvent. In this case, it ispreferable that surface acting agent such as oleic acid is added. Notethat slurry for wet molding may be adjusted by adding such as dispersantto dried fine milled material after the fine milling.

In the wet molding, said slurry for wet molding is then molded in amagnetic field. In this case, molding pressure is preferably around 9.8to 49 MPa (0.1 to 0.5 ton/cm²) and applied magnetic field may be around398 to 1592 kA/m. Further, pressure applied direction and magneticapplied direction when molding may be the same or orthogonal direction.

Firing of the molded body by the wet molding may be performed inoxidizing atmosphere such as air. Firing temperature is preferably 1050to 1270° C. and more preferably 1080 to 1240° C. Further, firing time(holding time of the firing temperature) is preferably 0.5 to 3 hours.

Note that when molded body is obtained by the aforementioned wet moldingand when said molded body is rapidly heated by firing withoutsufficiently drying, volatilization such as of dispersant vigorouslyoccur and a cracks may appear in the molded body. Therefore, in order toavoid such inconvenience, it is preferable to prevent occurrence ofcracks such as by sufficiently drying the molded body by heating in aslow heating rate, such as 0.5° C./min., from room temperature toapproximately 100° C. Further, when adding such as surface acting agent(dispersant), it is preferable to sufficiently remove them (degreasingtreatment) by heating in a heating rate such as approximately 2.5°C./min. within a temperature range of approximately 100 to 500° C. Notethat these treatments may be performed in the beginning of the firingprocess or separately before the firing process.

Although suitable manufacturing method of the ferrite sintered magnet isdescribed hereinbefore, as long as ferrite magnetic material of thepresent invention is used, manufacturing method is not particularlylimited to the above and conditions thereof can be suitably varied.

Further, as for a magnet, when manufacturing a bond magnet rather than aferrite sintered magnet, for instance, the obtained milled material andbinder are mixed after the aforementioned milling process and molded ina magnetic field, and then bond magnet including ferrite magneticmaterial powder of the invention can be obtained. Alternatively, bondmagnet can be obtained by heat treating ferrite magnetic materialpowder, manufactured by drying slurry obtained from the milling process,at a temperature such as around 1000 to 1200° C. wherein sintering doesnot occur, and then fractured magnetic powder and binder are mixed suchas by atomizer.

Formation of the magnet obtained from the present invention is notparticularly limited if it is manufactured from ferrite magneticmaterial of the present invention. For instance, ferrite magnet may havevarious shapes such as arc segment shape having anisotropy, plate shape,cylindrical shape, etc. Note that the arc segment shape is a shape inwhich plate shape is arc-like curved in one-way. According to theferrite magnetic material of the present invention, regardless of magnetshape, high Hk/HcJ can be obtained while maintaining high Br and HcJ.Particularly, even with arc segment shaped magnet, high Hk/HcJ can beobtained while maintaining high Br and HcJ.

Ferrite magnet according to the present embodiment may be used for amember of automotive motors, such as fuel pump, power window, ABS(Antilock Brake System), fan, wiper, power steering, active suspension,starter, door lock, electronic mirror, etc.

Further, it may be used for a motor member for OA/AV equipments such asFDD spindle, VTR capstan, VTR rotary head, VTR reel, VTR loading, VTRcamera capstan, VTR camera rotary head, VTR camera zoom, VTR camerafocus, capstan such as radio-cassette recorder, CD/DVD/MD spindle,CD/DVD/MD loading, CD/DVD optical pickup, etc.

Further, it may be used for a motor member for household electricalappliances such as air-conditioning compressor, freezer compressor,driving electric tools, drier fan, driving shaver, electric toothbrush,etc. Furthermore, it may be used for a motor member for FA electricalappliances such as for robot-shaft, join-driven, robot main driven,machine accessory table-driven, machine accessory belt-driven, etc. Asfor the other intended purpose, members such as motorcycle generator,speaker•headphone magnet, magnetron tube, magnetic field generator forMRI, clamper for CD-ROM, distributor sensor, ABS sensor, fuel•oil levelsensor, magnet latch, isolator, etc. can be exemplified. Alternatively,magnetic layers of magnetic recording medium can be used a target(pellet) when molding such as by evaporation method or sputteringmethod.

EXAMPLES

Below, although the present invention will be specified based on preciseexamples, the present invention is not limited to these examples.

Examples 1 to 6

<Mixing Process>

First, as for starting raw material, metal element mixture powderconstituting ferrite sintered magnet was prepared. As for the startingraw material, iron oxide (Fe₂O₃; including Mn, Cr, Al, Si and Cl asimpurity), lanthanum hydroxide (La(OH)₃), calcium carbonate (CaCO₃),strontium carbonate (SrCO₃), barium carbonate (BaCO₃) and cobalt oxide(Co₃O₄) were prepared and weighed to become compositions of each sampleas described in Tables 1 to 6. Further, as for Si component rawmaterial, silicon oxide (SiO₂, moisture content; approximately 20%, thesame raw material was used hereinafter.) was weighed to becomecompositions of each sample with respect to the total amount of startingraw material as described in Tables 1 to 6.

Note that samples were manufactured by respectively varying Sr ratio (x)and Ca ratio (1-w-x-y) in Example 1 (Table 1), La ratio (w) and La/Coratio (w/m) in Example 2 (Table 2), Ba ratio (y) in Example 3(Table 3),Co/Fe ratio (m/z) in Example 4 (Table 4), Fe ratio (z) in Example 5(Table 5) and SiO₂ content in Example 6 (Table 6).

<Calcining Process>

Powders of the starting raw material and SiO₂ were mixed by awet-attritor, milled and obtained slurry raw material mixture. This rawmaterial mixture was dried, and then calcined in air at 1225° C. for 2hours to obtain calcined body.

<Milling Process>

The obtained calcined body was coarse milled by small sized lotvibrational mill to obtain a coarse milled material. In order to makeratio of metal element constituting ferrite sintered magnet after firingas is shown in each sample value described in Tables 1 to 6, iron oxide(Fe₂O₃; including Mn, Cr, Al, Si and Cl as impurity), calcium carbonate(CaCO₃), strontium carbonate (SrCO₃), cobalt oxide (Co₃O₄) and siliconoxide (SiO₂) as subcomponent were respectively and suitably addedtogether with 0.45 wt % of sorbitol to the obtained coarse milledmaterial. Next, it was fine milled by a wet ball mill, in order to makespecific surface area (SSA) obtained by BET method to 8.0 to 9.0 m²/g;and then slurry was obtained. The obtained slurry was dried, granulated,and then ferrite material powder was obtained.

<Molding•Firing Process>

Molding was performed by CIM. First, ferrite material powder, PP(polypropylene used as binder resin), paraffin wax, acrylic resin andDOP (dioctyl phthalate used as plasticizing agent) respectively obtainedby the aforementioned method were prepared, and then they wererespectively weighed so that ferrite material powder=87 mass %, PP=5.1mass %, paraffin wax=5.1 mass %, acrylic resin=1 mass % and DOP=2 mass%. Next, they were kneaded by a pressurized and heated kneader at 165°C. for 2.5 hours. And the kneaded material (mixture) was molded to apellet shape by pelletizer and pellet 10 as shown in FIG. 4 wasobtained.

Next, by using magnetic field injection molding device 2 shown in FIG.4, pellet 10 was injection molded in mold 8. Before the injection inmold 8, cavity 12 was molded inside, and magnetic field was applied inmold 8. Note that pellet 10 was heat melted inside of extruder 6 andinjected in cavity 12 of mold 8 by screw. Temperature of injection was185° C., mold temperature was 40° C., and applied magnetic field wheninjecting was 1273 kA/m. A preliminary molded body obtained by amagnetic field injection molding process was circular shape withdiameter of 30 mm and thickness of 3 mm.

Removing wax treatment was performed to the preliminary molded body byheat treating for a total of 50 hours at the highest achievingtemperature of 230° C. in humidified air atmosphere. Removing bindertreatment was performed to the wax removed molded body in air with aslow heating rate from 150 to 500° C. Subsequently, firing was performedat 1190 to 1230° C. for one hour in air and obtained a ferrite sinteredmagnet.

Example 7

In example 7, except for changing a volume percentage of organiccomponent in the molded body as is shown in Table 7 in molding process,ferrite sintered body was obtained as is the same with examples 1 to 6.Note that the organic component is a total of PP(polypropylene),paraffin wax, acrylic resin and DOP(dioctyl phthalate); and mixtureratios of PP, paraffin wax, acrylic resin and DOP were made constant asis shown in example 1 even when the organic component ratio in themolded body varied.

In example 7, by varying volume percent of organic component in themolded body, degree of crystal orientation, crystal grain size andaspect ratio of sintered magnet were varied.

Example 8

In example 8, except for not adding sorbitol in the milling process andferrite material powder (filler) was silane coupling agent treated,ferrite sintered magnet was manufactured, as is the same with examples 1to 6, and evaluated thereof. In concrete, in example 8, except for notadding sorbitol and permolding fine milling to the coarse milledmaterial, adding 1 wt % of silane coupling agent (KBM-503, KBM-1003 byShin-Etsu Silicone Ltd.), with respect to the coarse milled material, tothe milled slurry after the fine miffing, and further mixing andpermolding dispersant treatments for 0.5 hrs. in a wet ball mill,ferrite sintered magnet was obtained, as is the same with examples 1 to6.

Example 9

In example 9, except for changing CIM to wet molding, ferrite sinteredmagnet was manufactured, as is the same with examples 1 to 6, andevaluated thereof. Namely, molding firing process in example 9 wasperformed as is described hereinafter.

First, fine milling was performed using toluene as dispersant; andmilled slurry was obtained. When said fine milling was performed, 1.3 wt% of oleic acid with respect to coarse milled material was added.Solvent amount in the obtained slurry was adjusted in order to makesolid content concentration to 74 to 76 mass %. The slurry was molded ina magnetic field by using a wet magnetic field molding device and makingapplied magnetic field to 1.2 T. And 30 mm diameter and 15 mm height ofcylindrical molded body was manufactured. Next, after the obtainedmolded body was sufficiently dried at room temperature, firing wasperformed in air at 1200 to 1230° C. for 1 hour; and then a ferritesintered magnet of sintered body was obtained.

Fluorescence X-ray quantitative analysis was performed to each ferritesintered magnet in examples 1 to 9; and then it was confirmed that acomposition of each ferrite sintered magnet was confirmed to be thecomposition respectively shown in Tables 1 to 9.

<Measurement of Magnetic Properties (Br, HcJ and Hk)>

First, density measurement was performed to each sample of examples 1 to9 by Archimedes method. Next, top and bottom surfaces of each ferritesintered magnet of examples 1 to 9 are processed; and then magneticproperties (residual flux density Br, coercive force HcJ, squarenessratio Hk/HcJ) were measured at 25° C. of air atmosphere using B-H tracerhaving 1989 kA/m of maximum applied magnetic field. Results are shown inTables 1 to 9. Here, Hk is an external magnetic field strength whenmagnetic flux density becomes 90% of remanent flux density in the secondquadrant of magnetic hysteresis loop.

<Degree of Crystal Orientation>

For each sample of sample number 1-4 of example 1, sample number 5-5 ofexample 5 and samples of examples 6 to 9, one surface of circular platedferrite sintered magnet were smoothly polished, XRD (X-ray diffraction)measurement was performed (X-ray source: CuKα) to said smoothly polishedsurface, and diffraction peaks derived from the ferrite sintered magnetwere identified. Degree of crystal orientation Or(f) of the sinteredmagnet was obtained from plane indices and peak strength of theidentified diffraction peaks. Note that sample number 1-4 in Table 1 andsample number 5-4 in Table 5 are the same sample; therefore, degree ofcrystal orientation is also shown in the space of sample 5-4 in Table 5.

<Crystal Grain Size, Aspect Ratio>

Crystal grain size and aspect ratio of each ferrite sintered magnet wereobtained as stated below.

First, cross-section parallel to c-axis (an easy axis of magnetization)direction of the ferrite sintered magnet were cut out, and then mirrorpolishing and etching treatment by hydrofluoric acid (concentration of36%) were performed to the cross-section. Next, the etching treatedsurface was observed by scanning electron microscope (SEM) and across-sectional image of crystal grains was obtained. Cross-sectionalimage by SEM of sample number 1-4 (or 3-3, 4-4, 5-4, 7-8) and that ofsample number 7-1 are respectively shown in FIGS. 3( a) and 3(b).

And then, an image analysis process was performed to the crystal graincross-sectional image obtained by SEM observation; and with each crystalgrains, as is shown in FIG. 2, maximum value “1” (μm) and minimum value“s” (μm) of crystal grain size, which go through a gravity center ofcross-section of the crystal grains, were respectively measured. Usingsuch method, maximum value “1” and minimum value “s” of crystal sizes of500 crystal grains were obtained, arithmetic mean value (an averagemaximum grain size L) of the maximum values “1” and arithmetic meanvalue (an average minimum grain size “S”) of the minimum values “s” wererespectively calculated, and aspect ratio L/S was obtained from theaverage maximum grain size “1” and the average minimum grain size “s”.The obtained average maximum grain size “L” and aspect ratio L/S areshown in Tables 1 to 9. Note that sample number 1-4 in Table 1 andsample number 5-4 in Table 5 are the same sample; therefore, averagemaximum grain size “L” and aspect ratio L/S are also shown in the spaceof sample 5-4 in Table 5.

Composition, magnetic property, degree of crystal orientation, crystalgrain size and aspect ratio of each sample in examples 1 to 9 are allshown in Tables 1 to 9.

TABLE 1 Example 1 Ratio of metal element constituting a Magnetic CrystalAverage ferrite sintered magnet Characteristic Orientation Maximum Caz + m SiO₂ Hk/ Degree of Particle Aspect Sample 1 − w − ((FeCo)/ La/(mass Br HcJ HcJ Sintered Diameter Ratio No. x − y La w Sr x Ba y Fe zCo m (CaLaSrBa)) Co %) (mT) (kA/m) (%) Body L (μm) L/S 1-1 0.601 0.3980.0003 0.0008 9.25 0.25 9.50 1.60 0.65 467.0 262.4 42.5 Not Not NotMeasured Measured Measured 1-1a 0.551 0.398 0.050 0.0008 9.25 0.25 9.501.60 0.65 471.2 390.1 90.1 0.93 Not Not Measured Measured 1-2 0.5010.398 0.101 0.0008 9.25 0.25 9.50 1.59 0.65 472.3 391.9 90.5 0.94 1.382.38 1-3 0.473 0.398 0.129 0.0008 9.25 0.25 9.50 1.59 0.65 473.1 388.992.5 0.93 Not Not Measured Measured 1-4 0.453 0.396 0.150 0.0008 9.250.25 9.50 1.59 0.65 471.4 404.3 91.4 0.92 1.36 2.35 1-5 0.448 0.3950.156 0.0008 9.25 0.25 9.50 1.58 0.65 471.9 377.0 90.5 0.92 Not NotMeasured Measured 1-6 0.406 0.395 0.198 0.0008 9.25 0.25 9.50 1.58 0.65471.0 390.5 91.1 0.92 1.33 2.26 1-6a 0.354 0.395 0.250 0.0008 9.25 0.259.50 1.58 0.65 470.3 392.4 91.5 0.92 Not Not Measured Measured 1-7 0.2290.397 0.373 0.0008 9.25 0.25 9.50 1.59 0.65 468.9 360.9 92.7 0.91 1.292.24 1-8 0.149 0.396 0.4545 0.0008 9.25 0.25 9.50 1.59 0.65 464.9 303.394.5 Not Not Not Measured Measured Measured 1-9 0.033 0.396 0.57000.0008 9.25 0.25 9.50 1.59 0.65 463.5 211.1 99.7 Not Not Not MeasuredMeasured Measured Sample No. 1-4 of Table 1, Sample No. 3-3 of Table 3,Sample No. 4-4 of Table 4, Sample No. 5-4 of Table 5 and Sample No. 7-8of Table 7 are the same samples.

TABLE 2 Example 2 Ratio of metal element constituting a Magnetic CrystalAverage ferrite sintered magnet Characteristic Orientation Maximum Caz + m SiO₂ Hk/ Degree of Particle Aspect Sample 1 − w − ((FeCo)/ (massBr HcJ HcJ Sintered Diameter Ratio No. x − y La w Sr x Ba y Fe z Co m(CaLaSrBa)) La/Co %) (mT) (kA/m) (%) Body L (μm) L/S 2-1 0.716 0.1800.103 0.0008 9.25 0.25 9.50 0.72 0.65 418.1 283.7 93.7 Not Not NotMeasured Measured Measured 2-1a 0.596 0.300 0.103 0.0008 9.25 0.25 9.501.20 0.65 468.0 390.4 90.7 0.91 Not Not Measured Measured 2-2 0.5460.349 0.104 0.0008 9.25 0.25 9.50 1.40 0.65 468.3 395.2 91.5 0.91 1.312.27 2-3 0.503 0.395 0.101 0.0008 9.25 0.25 9.50 1.58 0.65 470.7 386.992.5 0.93 1.37 2.36 2-4 0.456 0.441 0.102 0.0008 9.25 0.25 9.50 1.770.65 471.8 398.3 91.9 0.95 1.35 2.35 2-4a 0.422 0.475 0.102 0.0008 9.250.25 9.50 1.90 0.65 470.2 388.5 91.1 0.94 Not Not Measured Measured 2-50.406 0.489 0.104 0.0008 9.25 0.25 9.50 1.96 0.65 471.8 367.7 90.8 0.941.34 2.37 2-6 0.346 0.550 0.103 0.0008 9.25 0.25 9.50 2.20 0.65 466.7355.7 90.1 Not Not Not Measured Measured Measured 2-7 0.293 0.602 0.1040.0008 9.25 0.25 9.50 2.41 0.65 465.5 331.7 94.5 Not Not Not MeasuredMeasured Measured 2-8 0.236 0.662 0.101 0.0008 9.25 0.25 9.50 2.65 0.65431.5 244.1 83.1 Not Not Not Measured Measured Measured

TABLE 3 Example 3 Ratio of metal element constituting a Magnetic CrystalAverage ferrite sintered magnet Characteristic Orientation Maximum Caz + m SiO₂ Hk/ Degree of Particle Aspect Sample 1 − w − ((FeCo)/ La/(mass Br HcJ HcJ Sintered Diameter Ratio No. x − y La w Sr x Ba y Fe zCo m (CaLaSrBa)) Co %) (mT) (kA/m) (%) Body L (μm) L/S 3-1 0.453 0.3910.155 0.0002 9.25 0.25 9.50 1.57 0.65 467.7 401.5 88.7 0.91 1.34 2.333-1a 0.453 0.391 0.155 0.0004 9.25 0.25 9.50 1.57 0.65 470.0 405.9 90.10.92 Not Not Measured Measured 3-2 0.453 0.391 0.155 0.0006 9.25 0.259.50 1.57 0.65 470.5 407.7 90.8 0.92 Not Not Measured Measured 3-3 0.4530.396 0.150 0.0008 9.25 0.25 9.50 1.59 0.65 471.4 404.3 91.4 0.92 1.362.35 3-4 0.451 0.394 0.154 0.0011 9.25 0.25 9.50 1.58 0.65 470.1 406.591.8 0.92 Not Not Measured Measured 3-5 0.451 0.394 0.154 0.0017 9.250.25 9.50 1.58 0.65 470.6 407.4 90.6 0.93 Not Not Measured Measured 3-60.451 0.392 0.154 0.0027 9.25 0.25 9.50 1.57 0.65 468.6 409.2 91.0 0.921.35 2.35 3-7 0.452 0.393 0.150 0.0045 9.25 0.25 9.50 1.58 0.65 467.6409.1 91.6 0.92 Not Not Measured Measured 3-8 0.451 0.394 0.149 0.00639.25 0.25 9.50 1.58 0.65 467.8 410.5 91.9 0.91 Not Not Measured Measured3-8a 0.448 0.394 0.149 0.0100 9.25 0.25 9.50 1.58 0.65 468.3 403.4 92.00.91 Not Not Measured Measured 3-9 0.452 0.392 0.145 0.0110 9.25 0.259.50 1.57 0.65 468.1 396.7 92.4 0.91 1.33 2.31 3-10 0.451 0.391 0.1430.0150 9.25 0.25 9.50 1.57 0.65 461.0 376.0 88.2 Not Not Not MeasuredMeasured Measured 3-11 0.594 0.392 0.005 0.0101 9.25 0.25 9.50 1.57 0.65455.5 363.7 76.6 Not Not Not Measured Measured Measured Sample No. 1-4of Table 1, Sample No. 3-3 of Table 3, Sample No. 4-4 of Table 4, SampleNo. 5-4 of Table 5 and Sample No. 7-8 of Table 7 are the same samples.

TABLE 4 Example 4 Ratio of metal element constituting a Magnetic CrystalAverage ferrite sintered magnet Characteristic Orientation Maximum Caz + m Co/ SiO₂ Hk/ Degree of Particle Aspect Sample 1 − w − ((FeCo)/ Fe(mass Br HcJ HcJ Sintered Diameter Ratio No. x − y La w Sr x Ba y Fe zCo m (CaLaSrBa)) m/z %) (mT) (kA/m) (%) Body L (μm) L/S 4-1 0.454 0.3960.149 0.0008 9.25 0.00 9.25 0 0.75 226.5 252.7 97.0 Not Not Not MeasuredMeasured Measured 4-2 0.453 0.395 0.152 0.0008 9.25 0.11 9.36 0.012 0.72450.5 387.7 95.5 Not Not Not Measured Measured Measured 4-2a 0.453 0.3950.152 0.0008 9.25 0.19 9.44 0.020 0.72 465.8 400.8 92.6 0.93 Not NotMeasured Measured 4-3 0.454 0.396 0.149 0.0008 9.25 0.20 9.45 0.022 0.68466.5 402.7 93.1 0.93 1.34 2.36 4-4 0.453 0.396 0.150 0.0008 9.25 0.259.50 0.027 0.65 471.4 404.3 91.4 0.92 1.36 2.35 4-4a 0.453 0.396 0.1500.0008 9.25 0.32 9.57 0.035 0.65 467.2 410.2 91.0 0.92 Not Not MeasuredMeasured 4-5 0.451 0.395 0.154 0.0008 9.25 0.37 9.62 0.040 0.60 463.5419.7 92.4 0.92 1.33 2.30 4-6 0.453 0.395 0.151 0.0008 9.25 0.60 9.850.065 0.55 433.5 381.7 90.6 Not Not Not Measured Measured Measured 4-70.455 0.395 0.149 0.0008 9.25 0.70 9.95 0.076 0.50 420.5 276.7 80.5 NotNot Not Measured Measured Measured Sample No. 1-4 of Table 1, SampleNo. 3-3 of Table 3, Sample No. 4-4 of Table 4, Sample No. 5-4 of Table 5and Sample No. 7-8 of Table 7 are the same samples.

TABLE 5 Example 5 Ratio of metal element constituting a Magnetic CrystalAverage ferrite sintered magnet Characteristic Orientation Maximum Caz + m SiO₂ Hk/ Degree of Particle Aspect Sample 1 − w − ((FeCo)/ La/(mass Br HcJ HcJ Sintered Diameter Ratio No. x − y La w Sr x Ba y Fe zCo m (CaLaSrBa)) Co %) (mT) (kA/m) (%) Body L (μm) L/S 5-1 0.457 0.3950.147 0.0008 7.80 0.21 8.01 1.88 1.01 445.1 349.7 94.1 Not Not NotMeasured Measured Measured 5-2 0.453 0.396 0.150 0.0008 8.62 0.23 8.851.70 0.91 465.1 381.0 94.0 Not Not Not Measured Measured Measured 5-2s0.453 0.396 0.150 0.0008 8.72 0.23 8.95 1.70 1.05 465.7 419.3 92.0 0.921.29 2.28 5-2a 0.453 0.396 0.150 0.0008 8.80 0.23 9.03 1.70 0.91 470.0383.1 93.8 0.92 Not Not Measured Measured 5-3 0.454 0.395 0.150 0.00089.01 0.24 9.25 1.63 0.75 470.3 383.8 93.3 0.93 1.30 2.36 5-4 0.453 0.3960.150 0.0008 9.25 0.25 9.50 1.59 0.65 471.4 404.3 91.4 0.92 1.36 2.355-5 0.454 0.395 0.150 0.0008 9.45 0.26 9.70 1.55 0.57 470.5 410.7 91.50.92 1.33 2.34 5-5a 0.454 0.395 0.150 0.0008 9.60 0.26 9.86 1.55 0.57470.6 398.5 90.9 0.92 Not Not Measured Measured 5-6 0.452 0.396 0.1500.0008 9.71 0.26 9.97 1.52 0.50 471.3 379.4 91.5 0.92 1.36 2.35 5-70.453 0.395 0.151 0.0008 9.97 0.27 10.24 1.48 0.35 462.5 355.3 91.5 NotNot Not Measured Measured Measured 5-7a 0.453 0.395 0.151 0.0008 9.880.27 10.15 1.48 0.63 466.1 411.2 90.6 0.92 1.34 2.33 5-8 0.455 0.3920.152 0.0008 10.40 0.28 10.68 1.41 0.30 466.0 349.8 88.2 Not Not NotMeasured Measured Measured 5-9 0.454 0.396 0.150 0.0008 11.40 0.29 11.691.36 0.30 466.0 291.8 88.2 Not Not Not Measured Measured Measured 5-100.454 0.395 0.150 0.0008 12.10 0.32 12.42 1.23 0.30 461.5 230.7 91.5 NotNot Not Measured Measured Measured Sample No. 1-4 of Table 1, SampleNo. 3-3 of Table 3, Sample No. 4-4 of Table 4, Sample No. 5-4 of Table 5and Sample No. 7-8 of Table 7 are the same samples.

TABLE 6 Example 6 Ratio of metal element constituting a Magnetic CrystalAverage ferrite sintered magnet Characteristic Orientation Maximum Caz + m SiO₂ Hk/ Degree of Particle Aspect Sample 1 − w − ((FeCo)/ La/(mass Br HcJ HcJ Sintered Diameter Ratio No. x − y La w Sr x Ba y Fe zCo m (CaLaSrBa)) Co %) (mT) (kA/m) (%) Body L (μm) L/S 6-1 0.455 0.3980.147 0.0008 9.21 0.25 9.46 1.61 1.07 446.5 379.7 92.5 Not Not NotMeasured Measured Measured 6-2 0.455 0.398 0.147 0.0008 9.22 0.25 9.461.61 0.87 465.9 404.1 91.3 0.92 1.31 2.30 6-3 0.455 0.398 0.147 0.00089.22 0.25 9.46 1.61 0.72 472.2 389.5 91.5 0.92 1.34 2.35 6-4 0.455 0.3980.147 0.0008 9.21 0.25 9.46 1.61 0.67 474.3 375.7 90.5 0.93 1.38 2.376-5 0.455 0.398 0.147 0.0008 9.22 0.25 9.46 1.61 0.47 475.5 291.2 77.90.95 1.49 2.51 6-6 0.468 0.381 0.150 0.0007 8.97 0.25 9.22 1.54 0.90467.4 421.5 90.0 0.92 Not Not Measured Measured 6-7 0.468 0.381 0.1500.0007 8.97 0.25 9.22 1.54 0.83 469.7 434.4 90.8 0.92 1.36 2.33 6-80.468 0.381 0.150 0.0007 8.97 0.25 9.22 1.54 0.78 471.5 397.7 91.5 0.92Not Not Measured Measured

TABLE 7 Example 7 Organic Ratio of metal element constituting acomponent Magnetic Crystal Average ferrite sintered magnet amounts inCharacteristic Orientation Maximum Ca z + m SiO₂ Formed HcJ Hk/ Degreeof Particle Aspect Sample 1 − w − ((FeCo)/ (mass Body Br (kA/ HcJSintered Diameter Ratio No. x − y La w Sr x Ba y Fe z Co m (CaLaSrBa))%) (vol %) (mT) m) (%) Body L (μm) L/S 7-1 0.453 0.396 0.150 0.0008 9.250.25 9.50 0.58 50 477.6 301.0 93.5 0.95 1.53 2.46 7-2 0.453 0.396 0.1500.0008 9.25 0.25 9.50 0.58 48 475.2 360.2 94.1 0.94 1.38 2.39 7-3 0.4530.396 0.150 0.0008 9.25 0.25 9.50 0.58 45 471.0 376.1 91.8 0.92 1.372.38 7-4 0.453 0.396 0.150 0.0008 9.25 0.25 9.50 0.58 44 468.2 390.192.0 0.91 1.32 2.31 7-5 0.453 0.396 0.150 0.0008 9.25 0.25 9.50 0.58 42392.0 409.5 78.5 0.75 1.30 2.28 7-6 0.453 0.396 0.150 0.0008 9.25 0.259.50 0.65 50 478.5 326.4 92.2 0.95 1.47 2.39 7-7 0.453 0.396 0.1500.0008 9.25 0.25 9.50 0.65 48 476.0 385.5 93.9 0.94 1.37 2.35 7-8 0.4530.396 0.150 0.0008 9.25 0.25 9.50 0.65 45 471.4 404.3 91.4 0.92 1.362.35 7-9 0.453 0.396 0.150 0.0008 9.25 0.25 9.50 0.65 44 468.4 414.892.6 0.92 1.30 2.29 7-10 0.453 0.396 0.150 0.0008 9.25 0.25 9.50 0.65 42394.2 433.1 80.3 0.78 1.25 2.24 Sample No. 1-4 of Table 1, Sample No.3-3 of Table 3, Sample No. 4-4 of Table 4, Sample No. 5-4 of Table 5 andSample No. 7-8 of Table 7 are the same samples.

TABLE 8 Example 8 Organic Ratio of metal element constituting acomponent Magnetic Crystal Average ferrite sintered magnet amounts inCharacteristic Orientation Maximum Ca z + m SiO₂ Formed HcJ Hk/ Degreeof Particle Aspect Sample 1 − w − ((FeCo)/ (mass Body Br (kA/ HcJSintered Diameter Ratio No. x − y La w Sr x Ba y Fe z Co m (CaLaSrBa))%) (vol %) (mT) m) (%) Body L (μm) L/S 8-1 0.454 0.395 0.150 0.0006 9.080.24 9.32 0.74 45 476.0 410.1 94.4 0.96 1.28 2.18 8-2 0.453 0.397 0.1500.0009 9.12 0.24 9.36 0.69 45 477.7 398.6 95.1 0.95 1.31 2.26

TABLE 9 Example 9 Ratio of metal element constituting a Magnetic CrystalAverage ferrite sintered magnet Characteristic Orientation Maximum Caz + m Hk/ Degree of Particle Aspect Sample 1 − w − ((FeCo)/ La/ SiO₂ BrHcJ HcJ Sintered Diameter Ratio No. x − y La w Sr x Ba y Fe z Co m(CaLaSrBa)) Co (mass %) (mT) (kA/m) (%) Body L (μm) L/S 9-1 0.454 0.3950.150 0.0008 9.30 0.24 9.54 1.64 0.66 471.9 385.1 90.5 0.92 1.35 2.329-2 0.471 0.385 0.143 0.0011 9.00 0.25 9.24 1.57 0.84 466.0 424.8 90.10.92 1.31 2.29

Table 1 proves that, when Sr ratio (x) is over 0.0003 and less than0.373 and Ca ratio (1-w-x-y) is over 0.229 and less than 0.601, a highHk/HcJ can be obtained while maintaining good Br and HcJ. Table 1further proves that, when Sr ratio (x) is 0.05 to 0.25 and Ca ratio(1-w-x-y) is 0.354 to 0.551, higher Hk/HcJ can be obtained whilemaintaining good Br and HcJ.

Table 2 proves that, when La ratio (w) is over 0.180 and less than 0.550and La/Co (w/m) is over 0.72 and less than 2.20, a high Hk/HcJ can beobtained while maintaining good Br and HcJ. Table 2 further proves that,when La ratio (w) is 0.3 or more and less than 0.5 and La/Co (w/m) is1.2 to 1.9, higher Hk/HcJ can be obtained while maintaining good Br andHcJ.

Table 3 proves that, when Ba ratio (y) is over 0.0001 and less than0.0150, a high Hk/HcJ can be obtained while maintaining good Br and HcJ.Further, it was confirmed that sample 3-11, wherein Sr ratio (x) issmaller than Ba ratio (y) is insufficient, particularly in view of Brand Hk/HcJ. Table 3 further proves that when Ba ratio (y) is 0.0004 to0.01, higher Hk/HcJ can be obtained while maintaining good Br and HcJ.

Table 4 proves that, when Co/Fe(m/z) is over 0.012 and less than 0.065,high Hk/HcJ can be obtained while maintaining good Br and HcJ. Table 4further proves that when Co/Fe(m/z) is 0.020 to 0.035, high Hk/HcJ canbe obtained while maintaining good Br and HcJ.

Table 5 proves that, when Fe ratio(z) is over 8.62 and less than 9.97,high Hk/HcJ can be obtained while maintaining good Br and HcJ. Table 5further proves that when Fe ratio(z) is 8.8 to 9.6, high Hk/HcJ can beobtained while maintaining good Br and HcJ.

As is shown in Table 6, in the ferrite magnetic material, when ratio y1mass % of Si component with respect to SiO₂ is shown on Y-axis, totalamount x1 of z and in is shown on X-axis, and relation between x1 and y1is within a range surrounded by 4 points a(8.9, 1.2), b(8.3, 0.95),c(10.0, 0.35) and d(10.6, 0.6) shown on the X-Y coordinate having X andY axes, high Hk/HcJ can be obtained while maintaining good Br and HcJ.

Table 7 proves that degree of crystal orientation Or(f)=Σ(001)/Σ(hkl)obtained from X-ray diffraction measurement in the ferrite magneticmaterial is over 0.78, high Hk/HcJ can be obtained while maintaininggood Br and HcJ.

Further, it was confirmed from Table 7 that, in the ferrite magneticmaterial, an average maximum grain size L is less than 1.47 or DS isless than 2.46, high HcJ can be obtained.

Table 8 proves that even when silane coupling agent treated ferritemagnetic powder is used, high Hk/HcJ can be obtained while maintaininggood Br and HcJ.

Table 9 proves that even when samples obtained by wet molding are used,high Hk/HcJ can be obtained while maintaining good Br and HcJ.

DESCRIPTION OF THE SYMBOLS

-   2 . . . magnetic field injection molding device-   8 . . . mold-   10 . . . pellet-   12 . . . cavity-   20 . . . crystal grains

1. A ferrite magnetic material, in which its main phase comprises: aferrite phase having a hexagonal crystal structure, and metal elementcomposition constituting the ferrite magnetic material is expressed bythe following formula (1),Ca_(1-w-x-y)R_(w)Sr_(x)Ba_(y)Fe_(z)M_(m)  (1) wherein: R in formula (1)is at least one element selected from the group consisting of rare-earthelement, including Y, and Bi, which at least includes La, M in formula(1) is at least one element selected from the group consisting of Co,Mn, Mg, Ni, Cu, and Zn, which at least includes Co, w, x, y, z, and m informula (1) respectively satisfies the following formulas (2), (3), (4),(5), (6), (7) and (8)0.25<w<0.5  (2)0.01<x<0.35  (3)0.0001<y<0.013  (4)y<x  (5)8.7<z<9.9  (6)1.0<w/m<2.1  (7)0.017<m/z<0.055  (8), and an Si component is at least included as asub-component, and wherein: when content y1 mass % of the Si componentin the ferrite magnetic material, with respect to SiO₂, is shown onY-axis and a total content x1 of z and m is shown on X-axis, a relationbetween x1 and y1 is within a range surrounded by 4 points a(8.9, 1.2),b(8.3, 0.95), c(10.0, 0.35) and d(10.6, 0.6), placed on X-Y coordinatehaving the X and Y axes.
 2. A ferrite magnet comprising the ferritemagnetic material as set forth in claim
 1. 3. The ferrite magnet as setforth in claim 2, wherein a degree of crystal orientationOr(f)=Σ(001)/Σ(hkl) obtained by X-ray diffraction measurement is 0.9 ormore.
 4. The ferrite magnet as set forth in claim 2, wherein: within acut surface of crystal grains constituting the ferrite magnet, which iscut by a plane parallel to c-axis direction of hexagonal crystalstructures, maximum and minimum values of a grain size which go througha gravity center of each grain in a crystal cross-section arerespectively obtained, and when an average of said maximum and minimumvalues of the sizes in crystal grains of a predetermined number or moreare respectively determined as L(μm) and S(μm), said L and S satisfy thebelow formulas (9) and (10):L≦1.4  (9)L/S≦2.4  (10).
 5. A ferrite sintered magnet comprising the ferritemagnetic material as set forth in claim
 1. 6. The ferrite sinteredmagnet as set forth in claim 5, wherein a degree of crystal orientationOr(f)=Σ(001)/Σ(hkl) obtained by X-ray diffraction measurement is 0.9 ormore.
 7. The ferrite sintered magnet as set forth in claim 5, wherein:within a cut surface of crystal grains constituting the ferrite magnet,which is cut by a plane parallel to c-axis direction of hexagonalcrystal structures, maximum and minimum values of a grain size which gothrough a gravity center of each grains in a crystal cross-section arerespectively obtained, and when an average of said maximum and minimumvalues of the sizes in crystal grains of a predetermined number or moreare respectively determined as L(μm) and S(μm), said L and S satisfy thefollowing formulas (9) and (10):L≦1.4  (9)L/S≦2.4  (10).